T430s, Win7, having trouble with product key/Windows activation

Hey guys, hoping you can help me with a problem I'm having. I have a T430s that I ordered with Windows 7. I've been trying to set up Windows Media Center with a TV tuner, and the activation in WMC (which had a key show up automatically) isn't working. Further research shows that Windows apparently isn't activated, and my key (I didn't type it in, I guess it's stored on the computer) is invalid. Okay. After looking for a while, I did eventually find that there's a product key under the battery. Tried that, no good.

I have a feeling this may be related to my hard drive. The original SSD failed a few years ago, Lenovo sent someone out, replaced it (and took the bad SSD with all my files on it - thanks guys), and loaded windows on it using their disc. I don't know what key was used, but if it was a different one, that might be the problem. I do have the discs that came with the computer, and as far as I know they're matched to it, but I don't know if the hard drive has anything to do with that. I'm a little out of my element here, to be honest.